<html>
<script type="text/javascript">
  var canvas, ctx, flag = false,
    prevX = 0,
    currX = 0,
    prevY = 0,
    currY = 0,
    dot_flag = false;

  var x = "black",
    y = 2;

  function init() {
    canvas = document.getElementById('can');
    ctx = canvas.getContext("2d");
    w = canvas.width;
    h = canvas.height;

    canvas.addEventListener("mousemove", function (e) {
      findxy('move', e)
    }, false);
    canvas.addEventListener("mousedown", function (e) {
      findxy('down', e)
    }, false);
    canvas.addEventListener("mouseup", function (e) {
      findxy('up', e)
    }, false);
    canvas.addEventListener("mouseout", function (e) {
      findxy('out', e)
    }, false);
  }

  function color(obj) {
    switch (obj.id) {
      case "green":
        x = "green";
        break;
      case "blue":
        x = "blue";
        break;
      case "red":
        x = "red";
        break;
      case "yellow":
        x = "yellow";
        break;
      case "orange":
        x = "orange";
        break;
      case "black":
        x = "black";
        break;
      case "white":
        x = "white";
        break;
    }
    if (x == "white") y = 14;
    else y = 2;

  }

  function draw() {
    ctx.beginPath();
    ctx.moveTo(prevX, prevY);
    ctx.lineTo(currX, currY);
    ctx.strokeStyle = x;
    ctx.lineWidth = y;
    ctx.stroke();
    ctx.closePath();
  }

  function erase() {
    var m = confirm("Want to clear");
    if (m) {
      ctx.clearRect(0, 0, w, h);
      document.getElementById("canvasimg").style.display = "none";
    }
  }

  function save() {
    document.getElementById("canvasimg").style.border = "2px solid";
    var dataURL = canvas.toDataURL();
    document.getElementById("canvasimg").src = dataURL;
    document.getElementById("canvasimg").style.display = "inline";
  }

  function findxy(res, e) {
    if (res == 'down') {
      prevX = currX;
      prevY = currY;
      currX = e.clientX - canvas.offsetLeft;
      currY = e.clientY - canvas.offsetTop;

      flag = true;
      dot_flag = true;
      if (dot_flag) {
        ctx.beginPath();
        ctx.fillStyle = x;
        ctx.fillRect(currX, currY, 2, 2);
        ctx.closePath();
        dot_flag = false;
      }
    }
    if (res == 'up' || res == "out") {
      flag = false;
    }
    if (res == 'move') {
      if (flag) {
        prevX = currX;
        prevY = currY;
        currX = e.clientX - canvas.offsetLeft;
        currY = e.clientY - canvas.offsetTop;
        draw();
      }
    }
  }
</script>
<body onload="init()">
<canvas id="can" width="400" height="400" style="position:absolute;top:10%;left:10%;border:2px solid;"></canvas>
<div style="position:absolute;top:12%;left:43%;">Choose Color</div>
<div style="position:absolute;top:15%;left:45%;width:10px;height:10px;background:green;" id="green"
     onclick="color(this)"></div>
<div style="position:absolute;top:15%;left:46%;width:10px;height:10px;background:blue;" id="blue"
     onclick="color(this)"></div>
<div style="position:absolute;top:15%;left:47%;width:10px;height:10px;background:red;" id="red"
     onclick="color(this)"></div>
<div style="position:absolute;top:17%;left:45%;width:10px;height:10px;background:yellow;" id="yellow"
     onclick="color(this)"></div>
<div style="position:absolute;top:17%;left:46%;width:10px;height:10px;background:orange;" id="orange"
     onclick="color(this)"></div>
<div style="position:absolute;top:17%;left:47%;width:10px;height:10px;background:black;" id="black"
     onclick="color(this)"></div>
<div style="position:absolute;top:20%;left:43%;">Eraser</div>
<div style="position:absolute;top:22%;left:45%;width:15px;height:15px;background:white;border:2px solid;" id="white"
     onclick="color(this)"></div>
<img id="canvasimg" style="position:absolute;top:10%;left:52%;" style="display:none;">
<input type="button" value="save" id="btn" size="30" onclick="save()" style="position:absolute;top:55%;left:10%;">
<input type="button" value="clear" id="clr" size="23" onclick="erase()" style="position:absolute;top:55%;left:15%;">
</body>
</html>
